Motor speed adjusting device



April 1941? H. L. COLLINS 2,238,383

MOTQR SPEED ADJUSTING DEVICE Filed Oct. 17. 19558 N VENTOR.

ATTORNEYS Patented Apr. 15, 1941 MOTOR SPEED ADJUSTING DEVICE Barry L. Collins, St. Louis, Mo., assignor to Knapp-Monarch Company, St. Louis, Mo a corporation of Missouri Application October 17, 1938, Serial No. 235,469

3 Claims.

An object of my invention is to provide an adjusting device for changing the speed of a motor particularly of the contact breaker type common- 1y used for dry shavers and the like.

Another object is to provide means to change the speed of the motor which consists of mechanism to vary the position of one contact relative to the other so that the contacts are engaged a variable portion of the rotation of the motor shaft.

More particularly it is my object to provide in connection with a motor having a cam for moving one contact relative to another one and thereby intermittently breaking the circuit, a means to adjust the relative positions of the contacts so that they remain incircuit closing position during variable portions of the rotation of the cam.

Another object is to provide in connection with a motor having a stationary contact bracket and a movable contact, means to vary the position of the contact carried by the stationary bracket con sisting of an eccentric or the like rotatable to dia 7 ferent positions for bending the stationary contact bracket closer to or farther from the movable contact. 7

With these and other objects in view my invention with respect to its salient features which I believe to be novel and patentable will be pointed out in the appended claims. For a detailed understanding of the invention reference is made to the following description and to the accompanying drawing in which:

Figure 1 is a front elevation of a dry shaver with my contact adjusting mechanism applied thereto.

Figure 2 is an enlarged front elevation showing the cover plate of the dry shaver removed and an adjusting shaft of the adjusting mechanism shown in section.

Figure 3 is a sectional view on the line 3--3 of Figure 2 showing the adjusting mechanism supported by the shaver motor casing and coacting with the contacts of the motor.

Figure 4 is a view similar to Figure 2 showing a modified construction.

Figure 5 is a sectional view on the line 5-5 of Figure 4.

Figure 6 is a view similar to Figure 2 showing another modified construction; and

Figure 7 is an enlarged sectional view on the line 11 of Figure 6.

0n the accompanying drawing I have used the reference numeral iii to indicate generally a dry shaver motor housing and i2 a cover therefor. The cover i2 may be secured in position as by screws i3.

In the casing i2, a motor is provided including an end plate is secured by screws iii to a field core it on which are mounted windings H. The windings i! are adapted to be energized by electric current controlled by contacts l8 and IS. The contacts in turn are controlled as to separation and engagement by a cam 20 on the shaft 2| of the motor. The armature of the motor is indicated at 22.

The contact i0 is biased to engage the contact is by a spring 23. The spring also serves to retain a hooked end 24 of a bar 25 against a headed pivot pin 28. A strip of insulation 21 is mounted on the bar 25 for engaging the cam 20.

The contact i8 is the movable contact while the contact is is a stationary contact carried by a bracket 28. The bracket 28 may be made of brass or the like whereby it has inherent resiliency tending to separate the contact i9 from the contact i8.

My adjusting mechanism consists of a stub shaft 29 Journaled in a bearing sleeve 30. A cam ii is mounted on or formed integral with the shaft 29 and engages the bracket 28. The bearing sleeve 30 is carried by the cover l2 and on the outer end of the shaft 28 a knob 32 is mounted. The knob 32 may be attached to the shaft 28 by a screw 33 and the outer end of the shaft may be angular to fit a similar shaped anar socket 34 in the knob 32 so that rotation of the knob will effect rotation of the shaft 29 and thereby the cam 3!.

With the structure illustrated in Figures 1, 2 and 3 it is possible to vary the speed of the motor merely by rotating the cam 3| in one direction or the other. By rotating it so that the cam 3| bends the bucket 28 toward the contact i8, the contacts I3 and [9 are engaged for a greater portion of the rotation of the shaft 2| than when the bracket 28 is permitted to bend away from the contact l8. Thus in the first instance the motor is speeded up while in the latter instance it is slowed down and the speed of the motor is thereby adjustable within a wide range of limits.

In Figures 4 and 5 I show a modification in which a cam 3ia has a slotted head 32a instead of a knob for rotating it. In this instance the cover plate i2 must be removed in order to adjust the cam. After the adjustment is once made, the

tion in which the pivot pin for the contact bar 25 is adjusted instead of the stationary contact being adjusted. This is accomplished by providing a pivotipin 26a of modified construction when compared with the one shown in Figure 2. The modification consists of an eccentric portion 35 of the pin 26abeing provided for the hook end 2 of the bar 25. A head 32b is provided for the pin 26a and to the bearing plate H of the dry shaver motor. To retain its adjustment, a spring washer 36 may be provided on the pin 28a. The cover I! may be provided with an opening 31 through which a screw driver or the like can be thrust for coaction with the pivot pin head 32b.

By way of general illustration, a shaver head 38 is shown on the upper end of the casing in Figure l. The various modifications in my invention are each movable to effect a change in the relative positions of the contacts so that their engagement in proportion to the rotation of the motor shaft are changed to greater or less degrees depending on whether more or less speed is desired from the motor. I have found that such an adjustment 01! speed is particularly desirable when using a shaver head on diiierent beards or on different parts of the same beard. Some beards or parts thereof are out better with high speed 01 the motor while others are cut better with lower speed oi! the motor.

In the operation of the device shown in Figure 6 it is obvious that any adjustment of the right hand or hook end 2 of the bar 25 down wardly will move the contact l8 closer to the contact it. Thus in a somewhat reverse manner the relative positions of the contacts l8 and I! are changed to secure the same results as with the structures shown in Figures 2 and 4.

In accordance with the provisions or thepatent statutes I have described the principle of operation 0! my invention together with iilustrations thereof which I consider to represent the best embodiments thereof.

I desire that it be the pin can be rotated relative aseaees understood however, that the structure disclosed is only illustrative and that the invention may be carried out by other means and by the use of mechanical equivalents such as come within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent 0! the United States is:

1. An adjustable contact structure for a contact breaker type of motor comprising a contact carrying arm, a hook-shaped portion at one end of said arm, a contact mountedon the other end thereof, a strip oi insulation mounted on said arm intermediate said ends for engaging a motor cam, a rotatable mounting pivot, an eccentric portion on said pivot, said hook-shaped portion of said arm engaging said eccentric portion, a head on said pivot for retaining said hookshaped portion in position longitudinally of said pivot, and a spring engaging said arm adjacent said pivot for retaining said hook-shaped portion of said arm in engagement with said eccentric portion of said Pivot.

2. An adjustable contact structure for a con-' tact breaker type of motor comprising a contact carrying arm, a hook-shaped portion at one end of said arm. a rotatable mounting pivot, an eccentric portion on said pivot, said hook-shaped portion oi said arm engaging said eccentric portion, a head on said pivot for retaining said hookshaped portion in position longitudinally of said pivot. and a spring engaging said arm adjacent said pivot for retainin said hook-shaped portion of said arm in engagement with said eccent-ric portion oi said pivot.

3. Means iormounting the moving contact of a contact breaker type oi motor comprising a contact carrying arm, a notched portion at one end of said arm, a rotatable mounting pivot, and an eccentric portion on said pivot pin, said notched portion on said arm engaging said eccentric portion.

HARRY L. COLLINS. 

